Global positioning systems have been available in hand-held units for over 15 years, but as a result of current research at UCSB, a navigation system that includes a specialized audio interface may soon help guide people who are blind.

A group of scientists from the psychology and geography departments have teamed up to design and evaluate navigation systems for the visually impaired. These devices provide location information via audio queues instead of video displays. The device can direct a blind person to within several feet of a bus stop pole. The researchers predict that sighted people might use this technology eventually to navigate unfamiliar places, perhaps while traveling.

Psychology professor Jack Loomis has been working on GPS for the blind for almost two decades. Twenty years ago, GPS technology was not well established and required advances in computer and positioning technology for it to be suitable for personal navigation. Since then, the technology has improved and some navigation systems for the blind are already commercially available. The UCSB research has added to these commercial systems by designing audio interfaces and supplementing the GPS with an electronic compass.

“Unlike every other GPS for the blind system, we added a compass,” post-doctoral researcher James Marston said. “With most GPS systems you do not know which way you are facing.”

The compass and GPS are both connected to a portable computer that combines the information from the two sources and provides feedback to the user, Marston said. The computer can provide sound via stereo headphones that the user perceives as if it is coming from an imaginary location in space. For example, if the sound going to the left ear is louder and slightly less delayed than the sound going to the right ear, the listener will think the sound came from the left. The computer uses a stereo audio system called a spatialized display to guide the user by having them walk toward the apparent location of the sound.

GPS uses a series of locations on a map called waypoints to record the directions to a specific destination. The more turns a route has, the more waypoints are needed to accurately depict the route.

“It’s like a loudspeaker at the next waypoint,” Marston said. “There’s no way you can miss, you just follow the beep.”

The alternative to spatialized display often requires that directions be given verbally to the user, Loomis said. Instead of providing a beep that originates from the next waypoint, the computer would use a generated voice to tell the user which way to turn.

“Virtually all of the projects except ours have used synthetic speech,” Loomis said. “What we’ve shown in a number of studies over the last five years is that blind people really do like the spatialized displays.”

The synthetic speech can be difficult to use because it is not as natural as the spatialized display, Loomis said. For example, the computer may say, ‘Turn left 43 degrees.’ This is more difficult to follow than just walking toward a beep. The work in developing a spatialized display for navigation is unique to UCSB.

Loomis started work on the spatialized display for GPS after his colleague, geography professor Reginald Golledge, lost his sight in 1984. Golledge has been involved with the project ever since, providing both personal experience and expertise from his department.

“It took a long time to get it going because no one had ever done anything like this,” Loomis said. “People weren’t thinking along those lines. Speech is good and it can give you some information, but the idea of a direct display about where things are in your environment [is key].”

Some difficulties with spatialized displays were discovered early in the project.

“The downside of virtual sound … is that blind people use their hearing to pick up subtle environmental sounds, and they also use high frequencies to detect surfaces — it’s called echolocation,” Loomis said. “Because they rely on that to avoid bumping into things, and to be aware of their environment, most blind people are reluctant to consider wearing earphones.”

Marston has been working on a way to make headphones for the blind that would not interfere with their hearing. Currently, he is experimenting with audio tubes that do not cover the ear, but still provide sound that can convey directional information.

The other part of user interface to be incorporated into a navigation system is a way for the user to input where he or she wants to go. Sighted people can select this with a touch screen or keyboard, but these options are not available to the blind.

“Our system is voice activated,” Marston said. “If I say, ‘Take me to the library,’ [the system] will calculate the shortest route, tell me the number of turns and start directing me to the first waypoint.”

Other GPS for the blind systems use a Braille keyboard, but this is slower and not as convenient as simply speaking the destination, Loomis said.

To program the GPS to remember how to get to a location such as the library, the blind user must get help from a friend who will lead him or her to the destination. Once the system is programmed, the blind person can request the system to give directions to a location. The route to a location could then be saved as a computer file.

“Once this technology grows, just like sharing music, I foresee sharing direction files,” Marston said.